1. Field of the Invention
The present invention relates to an image forming apparatus utilizing an electrophotographic technology, and more particularly to a charge elimination of a recording material.
2. Description of the Related Art
A configuration of a prior image forming apparatus is shown in FIG. 7.
A prior image forming apparatus is provided with a photosensitive drum 101 serving as an image bearing member. The photosensitive drum 101 is shaped in a cylindrical form, and is supported rotatably in a direction R1 indicated by an arrow, in a main body (not shown) of the apparatus. Along a periphery and a rotating direction of the photosensitive drum 101, there are provided, for example, a charging apparatus 102 for uniformly charging the photosensitive drum 101, an exposure apparatus 103 for emitting a laser beam corresponding to a document image (the image of an original) for exposing the photosensitive drum 101 thereby forming an electrostatic latent image, a developing apparatus 105 for depositing a toner onto the electrostatic latent image thereby forming a toner image, a transfer roller 106 constituting a transfer member which transfer the toner image on the photosensitive drum 101 onto a paper P, and a cleaner 107 for eliminating a residual toner remaining on the photosensitive drum 101 after the transfer.
On the other hand, in an upstream side of the photosensitive drum 101 in a conveying direction (namely at the right-hand side in FIG. 7), there is mounted a sheet cassette 109 for stacking papers P to be used for image formation. A sheet feeding roller 110 is provided at an upper front side of the sheet cassette 109, and a transfer material conveying path 111 is provided at a downstream side thereof (left side in FIG. 7). In the transfer material conveying path 111, there are provided two pairs of conveying rollers 112 for conveying the paper P by nipping both sides thereof, a registration sensor 113 for detecting a leading edge of the paper P, and a charge elimination brush 115 constituting a charge elimination member which eliminates a charge on the paper P by a contact therewith. Also a pre-transfer guide 116 is provided as a part of the transfer material conveying path 111, for guiding the paper P to a transfer area. At a downstream side of the photosensitive drum 101, there is provided a fixing apparatus (not shown) for fixing a toner image transferred onto the paper P.
When a print signal is inputted from an unillustrated host computer to the image forming apparatus, the photosensitive drum 101 starts to rotate in a direction R1 as illustrated and is subjected to a uniform surface charging by the charging apparatus 102. At this operation, the sheet feeding roller 110 is rotated to feed the paper 9 from the sheet cassette 109. The fed paper 9 is pinched and conveyed by the conveying rollers 112, and is stopped upon reaching a position of putting down the sensor 113. On the other hand, the charged surface of the photosensitive drum 101 is irradiated with a laser beam modulated by an image signal, whereby an electrostatic latent image is formed. Then, on the electrostatic latent image, a toner is deposited by a developing roller 105a of the development apparatus 105 thereby forming a toner image. In synchronization with such toner image, the conveying rollers 112 are driven, and the paper P comes into contact with the charge eliminating brush 115 for a charge elimination on a rear side thereof, then enters a transfer area through the pre-transfer guide 116, and receives a transfer of the toner image on the photosensitive drum 101, by a transfer roller (transfer apparatus) to which a transfer bias is supplied from an unillustrated high voltage source. The paper P is subsequently subjected to a fixation of the toner image by an unillustrated fixing apparatus, and is discharged from the main body of the apparatus. On the other hand, the photosensitive drum 101, from which the toner image has been transferred, is subjected to an elimination of a residual toner by the cleaner 107, thus being prepared for a next image forming process, which is to be started by a charging by the charging apparatus 102.
In such prior technology, however, the leading end of the paper P may be caught by the charge eliminating brush 115 thereby causing a paper jam. When a thin paper P contact the charge eliminating brush 115, a leading end portion may be bent thereby leading to a paper jamming.
The charge eliminating brush 115, constituting a charge elimination member in FIG. 7, is so positioned as to intercept the path of the paper, in order to improve the charge eliminating effect for the paper P. However, such positioning of the charge elimination member as to intercept the path of the paper may cause a case where the leading end of the paper is caught by the charge eliminating members, and a paper jamming may be generated from the position of such catching.